Fuel Temperature Escalatfon in Severe Accidents

Abstract

One of the key phenomena observed in severe fuel damage experiments is the relocation of molten material upon melting of Zircaloy cladding. solid/liquid interfacial forces tend to dominate the relocation of molten materials in thin-walled horizontal CANDU fuel, rather than gravity in LWR fuel. This paper discusses observed relocation patterns in CANDU fuel in view of available data on the interfacial properties of molten Zircaloy. Conditions governing the various possible relocation modes are identified and a simple modelling approach is proposed. The effect of melt relocation on the exothermic metal/water reaction (MWR) is explored analytically.